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Re: High speed Data link



> The 1200 baud PSK modem by KD2BD uses an EXAR XR2211 PLL which has a max
> of 300Khz and that is iff you happen to get a good batch.  I don't see
> how that chip could be pushed to 300Kbs.

It probably can't.

Actually, my PSK modem uses two XR2211s: one for extracting (regenerating)
the suppressed BPSK carrier from the incoming signal, and the second
for NRZI data clock extraction (regeneration and timing).  The actual
BPSK demodulation, however, occurs in a balanced demodulator, with
the first XR2211 supplying the required "local oscillator" injection.

The XR2211 itself cannot demodulate PSK signals.  It's primary use
is in AFSK demodulation (1200-baud VHF-FM packet radio, caller-ID,
etc.) applications.  It also makes an excellent NBFM demodulator.
Although I haven't tried it, it can probably make a nice SSTV
demodulator too (although I think I'd rather do the sync detection
separately with narrowband active filters to be able to reliably
copy really weak signals).

So many cool things to do... so little time (sob).  :-)


73, de John, KD2BD

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-=-=-=-=-=-=-=-=-=-=-=-=- John A. Magliacane, KD2BD -=-=-=-=-=-=-=-=-=-=-=-=-
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